In every human being w teeth, mastication inevitably causes food to infiltrate between the teeth. Failure to remove the resulting food deposits is the source of proximal caries and periodontal diseases.
Using a toothbrush does not allow these anatomical spaces to be cleansed, which spaces are, on the other hand, accessible to the interdental jets of water from devices known as pressurized fluid supply devices to interdental floss and other stiff interdental brushes and interdental tooth picks. Ideal interdental hygiene consists in simultaneously employing interdental floss and jets.
By means of a mechanical effect, interdental floss enables fibres of food wedged at the very contact point to be dislodged, something which a jet cannot do, and then, by small up and down movements, the mesial and distal faces of the two adjacent teeth to be scraped. It is the use of interdental floss which enables approximal caries to be prevented at the contact point. Floss is superior to the action of the jet in this context since it definitively dislodges the fibres wedged at the very contact point, whereas the jet cannot manage this. By its mechanical scraping action, floss is furthermore superior to the jet in the quality of the surface finish obtained.
On the other hand, the jet has the advantage of being able to dislodge rapidly the food deposits which have already passed below the contact point and which may be removed laterally by water pressure. However, in addition to the less satisfactory quality of the surface finish obtained, the jet may be dangerous to use. Indeed, especially when the pressure is set to its strongest, it is imperative that the jet be prevented from being directed obliquely in the tooth-gingiva direction, which would in the long term cause the gingiva to become detached. The danger then arises that daily use of the jet becomes a contributory factor in periodontal decay.
In order not to cause any harm, the jet would then have to be handled precisely and judiciously, in other words continually controlling the direction of the water jet perpendicular to the major axes of the teeth or obliquely in the gingiva-tooth direction.
It proves to be very difficult, or even impossible, in practice with the known pressurized fluid supply devices to control perfectly this optimum directing into all the interdental spaces of the same mouth, the jet being produced through a tooth pick which is simply held in the hand.
Through ageing or periodontal disease, the gingival papilla may retract and disappear. The resulting wide open embrasures are readily filled with food deposits which may be easily cleansed with a well directed jet or an interdental radial (hair) brush mounted on a handle or some other toothpick.
Among the various interdental floss systems, there are disposable floss-holders with a piece of interdental floss crimped onto the free ends of the two arms of a fork. Other interdental floss system have a fork-shaped floss-holder with two needle eyes through which the floss is to be threaded, which is a difficult operation. There are, moreover, interdental floss systems with a fork having notches for receiving the floss in its two arms, which arrangement simplifies the positioning of the floss but the securing of the floss in these notches is uncertain during assembly and use, in particular when it is being disengaged from the contact point.
Lastly, it is already known from U.S. Pat. No. 4,031,908 to provide, on the same dental cleansing device, the use of a piece of interdental floss held between the two arms of a fork, and the use of a jet of water emitted by one of the arms of the fork towards the other arm, adjacently to the position of the interdental floss. This known device has, however, a certain number of disadvantages.
As a result of the presence of a single jet of water, this device only allows rinsing in one direction with a single operation, rinsing in both directions requiring a double operation. Now it often happens that rinsing in only one direction does not enable the food deposits in the two interdental embrasures, the vestibular and lingual, to be dislodged correctly.
Moreover, in order to make this double operation possible, the fork of this known device must be a flat fork, whereas an interdental floss-holder must preferably have the shape of a curved fork in order to make correct access to all the teeth possible.
As a result of this need for a double operation, the jet of water may, in addition, be designed uniquely so as to act perpendicular to the major axes of the teeth since, if the jet is inclined, it would be directed correctly in the gingiva-tooth direction during the first operation, but would necessarily be directed in the wrong direction, that is the tooth-gingiva direction during the second operation, after turning the device around by 180.degree..
In addition to these problems caused by the presence of a single jet of water, it must be noted that with this known device, replacing a length of broken interdental floss by a new length of interdental floss, and the correct tensioning of this length of interdental floss, present difficulties to the extent that, on one hand, the two needle eyes provided at the free end of the two arms of the fork are very fine so that it is not easy to thread the interdental floss through these needle eyes and that, on the other hand, locking of the interdental floss with tension is effected by clamping the two ends of the floss between the body (handle) of the device and the fork-shaped head, the said two parts being connected by screwing.